Chronic Low back pain is one of the most common and difficult problems physicians treat. Conventional medical and surgical treatments have limited success with this disorder. There is a developing consensus among physicians that assessment of the behavior of the chronic low back pain patient is important. The behavioral assessment literature on this topic is small and suffers three major deficiencies: 1) a small, poorly diagnosed and highly select patient group (those referred for specialized behavioral treatment) has been studied, 2) a single behavior such as activity level is typically studied and relationships among multiple behaviors, such as activity level, medication intake, pain ratings and motor pain behaviors, have not been analyzed, and 3) the relationship between patient characteristics and behavior has not been studied. The proposed study attempts to overcome these deficiencies by examining behavior patterns in a large sample (n=250) of chronic low back pain patients having current symptoms of lumbar disc disease. Patients will be randomly selected from those presenting to the Orthopedic and Neuro-surgery clinics at Duke Medical Center. All patients will keep records of activity level, medication intake, and pain ratings using a diary for two weeks prior to evaluation. During the patient's physical examination, a trained observer will use an observation method we recently developed to record the incidence of five motor pain behaviors; guarding, bracing, rubbing, grimacing, and sighing. To examine the relationships among the behaviors measured a principal components analysis will be conducted. Factors emerging from this analysis will be further analyzed to determine the extent to which they can be predicted on the basis of two demographic variables (age and sex), three medical status variables (chronicity of pain, disability status and number of previous surgeries) and severity of depression. This study represents a first step in advancing behavioral research on chronic low back pain. Subsequent studies are planned to: 1) compare behavior patterns of lumbar disc disease patients to other chronic low back pain patients, 2) analyze the development of maladaptive behavior patterns over time, and 3) assess whether behavior patterns measured at the time of medical/surgical evaluation are predictive of treatment outcome.